JP2015105739A - Condensing mixing device and boil-off gas re-liquefying apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a condensing mixing device for effectively re-liquefying boil-off gas, and a boil-off gas re-liquefying apparatus having the same.SOLUTION: The condensing mixing device has: a Venturi tube-type flow tube 7 including a diameter-reduced portion 7A, a throat portion 7B and a diameter-enlarged portion 7C that are formed from an upstream side toward a downstream side; and steam holes 10-1, 10-2... that are directed to a radial direction and a downstream-side direction of the flow tube and that are formed so as to have injection openings 10A-1, 10A-2, ... in an inner diameter surface of the diameter-enlarged portion at a plurality of axial X-direction positions of the flow tube. The condensing mixing device injects steam to a liquid flowing in the flow tube, from the injection openings of the steam holes, condenses the steam and mixes the same in the liquid. In the condensing mixing device, the diameter-enlarged portion 7C has stepped portions 10B-1, 10B-2,... in a plurality of axial-direction positions, and has stepped diameter-enlarged portions 7C-1, 7C-2,... successively diametrically enlarged at the stepped portions and extending toward the downstream side, and the injection openings 10A-1, 10A-2,... of the steam hole 10-1, 10-2,... are provided at an upstream-side position in a region of the stepped diameter-enlarged portion.

Description

  The present invention relates to a condensing and mixing apparatus for bringing vapor into contact with a low-temperature liquid, condensing and liquefying the vapor, and mixing it into a low-temperature liquid, and an evaporative gas reliquefaction apparatus having the same.

  When low temperature liquid such as liquefied natural gas (LNG) is stored in a tank, a part of the low temperature liquid in the tank evaporates due to heat input to the tank from the outside, and evaporated gas is generated in the tank. When the low-temperature liquid is LNG, an evaporating gas mainly composed of methane is generated.

  The generated evaporative gas can be compressed as it is and supplied to the demand side as city gas, but the compression power becomes very large. Therefore, in order to reduce such power, it can be considered that the evaporated gas is re-liquefied and pressurized in a liquid state and then gasified again to be supplied as city gas. In order to reliquefy, evaporative gas is compressed and cooled, and as a cooling method, evaporative gas is cooled by the cold heat of LNG discharged as a low temperature liquid from the tank, that is, compressed. Patent Documents 1 and 2 disclose a method of cooling evaporative gas by exchanging heat with LNG.

  Patent Document 1 discloses a method (indirect heat exchange method) in which compressed evaporative gas is cooled by heat exchange with LNG in a heat exchanger. However, in this indirect heat exchange method that requires a heat exchanger, a large heat exchanger is required to secure a sufficient heat transfer area for heat exchange, and there is a problem that the equipment becomes large and costs increase. . Furthermore, since heat transfer is indirect through the heat transfer surface, improvement in heat transfer performance on this heat transfer surface is also required.

  On the other hand, Patent Document 2 discloses a method (direct contact heat exchange method) in which compressed evaporative gas is blown into an LNG pipe and directly brought into contact with LNG to exchange heat, and evaporative gas is blown into LNG. As an injection method, an apparatus is disclosed in which one evaporative gas supply nozzle is arranged in the LNG pipe so as to be in a direction orthogonal to the flow direction of the discharge LNG flowing in the LNG pipe or in a direction opposite to the flow direction of the LNG. The evaporative gas supply nozzle is bent in an L shape in the LNG pipe, and the discharge port of the nozzle is located on the center line of the LNG pipe so that the evaporative gas is directed in the direction opposite to the flow of LNG. Is discharged. The discharged evaporative gas is cooled by heat exchange with LNG, condensed, liquefied and mixed with LNG.

  Since the direct contact heat exchange method of Patent Document 2 exchanges heat without passing through the heat transfer surface, the heat transfer performance at the interface where both the LNG and the evaporation gas are in contact with each other is improved. However, in the direct contact heat exchange system, the liquefaction efficiency is poor due to insufficient contact and mixing of the evaporating gas and the low temperature liquid due to the difference in density between the evaporating gas as the gas and the LNG as the low temperature liquid. Prone. In order to improve the efficiency, there is a demand for an efficient apparatus that mixes gas evaporative gas and low-temperature liquid LNG to condense and mix evaporative gas. It is difficult to say that contact and mixing of gas and liquid LNG can be sufficiently ensured, and desired liquefaction performance can be ensured.

  On the other hand, as a direct contact heat exchange system, a condensing and mixing device that condenses and mixes steam by injecting steam into a low-temperature liquid flowing in a venturi-type flow tube and directly contacting it is patented. It is disclosed in documents 3 and 4. In the apparatus of the type disclosed in Patent Documents 3 and 4, steam holes for injecting steam from the radial direction are formed in the flow pipe, and the steam is a venturi of a low-temperature liquid flowing in the flow pipe. It is sucked into the flow tube from the vapor hole by the phenomenon. The vapor immediately after being sucked is present as bubbles in the cryogenic liquid, and then condensed and mixed with the cryogenic liquid.

  First, in Patent Document 3, a large number of small-diameter steam holes are formed in a plurality of positions in the circumferential direction and in the liquid flow direction in the enlarged diameter portion that is downstream of the throat portion of the venturi tube. Yes. Since the steam is dispersed from the plurality of steam holes and sucked into the enlarged diameter portion, the bubble diameter of the steam immediately after being sucked is small. As a result, the condensation of the steam is completed in a short time, and the water hammer action in the enlarged diameter portion is suppressed.

  Next, in Patent Document 4, a section having a constant channel cross-sectional area is formed by forming a section with a constant diameter and extending downstream with a step immediately after the throat portion of the venturi tube and having a stepped diameter. Is provided at one position at the step where the flow path is rapidly expanded by the step.

  As another type of condensing and mixing apparatus, Patent Document 5 discloses that vapor as evaporating gas is injected into water as low-temperature liquid flowing through a mixing chamber in a pipe, and the vapor is condensed and mixed with water. Discloses a condensing and mixing device that produces hot water. This condensing and mixing device is provided with a fixed swirl vane for imparting swirl to water in the mixing chamber, and the efficiency of mixing water and steam is improved by the fixed swirl vane.

JP 55-145897 JP 08-173781 JP 04-045832 A JP2013-039497A JP 7-116486 A

  However, even in an apparatus such as Patent Documents 3 and 4, when the pressure of gaseous evaporative gas is increased and brought into direct contact with LNG as a low-temperature liquid, if sufficient condensing and mixing performance is not ensured, evaporative gas merged with LNG If the liquid is not liquefied completely and supplied to the liquid feed pump in a state where bubbles remain without being liquefied, not only liquid feeding becomes difficult, but also the liquid feeding pump may be broken.

  In this way, in order to suck a predetermined amount of vapor more efficiently with the liquid venturi phenomenon, the arrangement of the vapor holes for sucking the vapor, the optimal shape and structure for reducing the pressure loss in the venturi pipe, etc. An optimum structure as a condensing and mixing apparatus is required. Further, in the condensing and mixing apparatus provided with the swirl imparting mechanism that improves the condensing and mixing performance as in Patent Document 5, the fluid in the condensing and mixing apparatus passes through the fixed swirling blades, so that the pressure loss of the condensing and mixing apparatus increases. There is a problem.

  In view of such circumstances, the present invention increases the pressure of gaseous evaporative gas, and when this evaporative gas is brought into direct contact with a low temperature liquid such as LNG for reliquefaction, the evaporative gas is effectively condensed to a low temperature liquid. It is an object of the present invention to provide a condensing and mixing apparatus for mixing and an evaporative gas reliquefying apparatus having the apparatus and capable of effectively realizing reliquefaction.

  According to the present invention, the above-described problems are solved by a condensing and mixing apparatus having the following configuration and an evaporative gas reliquefaction apparatus having the same.

<Condensation mixer>
It has a venturi-type flow tube in which a diameter-reduced portion that gradually decreases from the upstream side toward the downstream side is followed by a throat portion that has a minimum diameter, and a diameter-expanded portion that gradually increases from the throat portion. In order to inject steam from the outside of the flow tube into the flow tube, steam holes directed in the radial direction and downstream direction of the flow tube are injected into the inner diameter surface of the enlarged diameter portion at a plurality of positions in the axial direction of the flow tube. In the condensing and mixing apparatus that injects steam from the injection opening of the vapor hole into the low-temperature liquid that flows downstream in the flow tube and condenses the vapor to mix with the low-temperature liquid, the enlarged diameter portion is The stepped portion is formed at a plurality of positions in the axial direction, and has stepped diameter-enlarged portions having inner peripheral surfaces that are sequentially expanded in diameter in the stepped portion and extending downstream in the axial direction. Condensation characterized in that a steam hole injection opening is provided at an upstream position within the region Coupling devices.

  In the present invention, the stepped portion has a radius difference between a preceding stepped enlarged portion adjacent upstream on the stepped portion and a succeeding stepped enlarged portion adjacent downstream on the stepped portion. The size is preferably 12 to 30% of the inner diameter of the diameter portion.

  In the present invention, it is preferable that the stepped enlarged portion extends in the axial direction over a section length of 2.5 to 8 times the radius of the stepped enlarged portion.

<Evaporative gas reliquefaction device>
Evaporative gas generated from cryogenic liquid stored in the storage tank is mixed with the low-temperature liquid discharged from the storage tank to condense and re-liquefy. An evaporative gas compressor, and a delivery pump for delivering cryogenic liquid from the storage tank. The evaporative gas is supplied from the upstream side to the flow pipe of the condensing and mixing device by the delivery pump, and the evaporative gas is condensed by the evaporative gas compressor. An evaporative gas reliquefaction apparatus, wherein the evaporative gas reliquefaction apparatus is adapted to inject into the flow pipe from a vapor hole of a mixing apparatus.

  If not according to the present invention, the vapor immediately after being sucked from the vapor hole cannot be condensed because the contact time and the contact area with the low-temperature liquid are small, and may exist as bubbles in the liquid. In the apparatus and the evaporative gas reliquefaction apparatus, the vapor hole is located at the upstream position in the region of the stepped enlarged diameter portion, that is, immediately after the vapor hole is suddenly enlarged at the stepped portion of the enlarged portion of the venturi pipe. Therefore, the space immediately after the sudden expansion at the stepped portion can be secured as a sufficiently large space for the vapor bubbles to mix with the cryogenic liquid, and the contact time between the vapor and the cryogenic liquid can be secured in this space. It can be ensured sufficiently, and the vapor can be cooled and condensed by the cryogenic liquid and mixed. Further, the vapor is efficiently sucked by the venturi phenomenon efficiently without being affected by the flow of the low-temperature liquid in the flow tube in the space of the stepped enlarged diameter portion.

  Further, in the present invention, a plurality of step-shaped enlarged diameter portions are provided, and vapor holes are formed in each step-shaped enlarged diameter portion. Therefore, a large number of vapor holes are dispersed in a circumferential direction and a liquid flow direction. Therefore, the bubble diameter of the vapor is reduced, the condensation of the vapor and the mixing with the low temperature liquid are promoted, and the water hammer action is suppressed.

  As described above, according to the present invention, a plurality of stepped diameter enlarged portions are provided in the flow tube of the condensing and mixing apparatus to sequentially increase the diameter, and the injection opening of the steam hole is positioned upstream in the region of each stepped enlarged diameter portion. Therefore, the evaporative gas is effectively introduced into the cryogenic liquid, mixed in the cryogenic liquid in the space where the diameter has been expanded relative to the preceding stepped enlarged portion, so that the evaporating gas is effective in the cryogenic liquid. Therefore, it is possible to prevent the pump from being damaged due to the evaporating gas flowing into the pump as a gas. Moreover, in the evaporative gas reliquefaction apparatus having the condensing and mixing apparatus having such a configuration, the reliquefaction of the evaporative gas can be completed efficiently in a short time, and as a result, the apparatus configuration can be made compact.

It is a schematic block diagram of the evaporative gas reliquefaction apparatus of one Embodiment apparatus of this invention. It is sectional drawing of the condensation mixing apparatus used for FIG. 1 apparatus, (A) is the whole apparatus, (B) is an expanded sectional view about a part of (A). 2 is a graph showing the experimental results regarding the efficiency improvement rate by providing a stepped diameter-enlarged portion for the device, (A) shows the step size ratio, (B) shows the efficiency improvement rate for the section length dimension ratio. Yes.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of an evaporative gas reliquefaction apparatus including a condensing and mixing apparatus as an embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes an evaporative gas reliquefaction device according to the present embodiment, which has a condensing and mixing device 2 having a structure shown in detail in FIG. Connected to the left side) are a delivery pump 3 for delivering the cryogenic liquid 11 to the condensing and mixing device 2 and an evaporative gas compressor 4 for injecting the evaporative gas 12.

  The cryogenic liquid 11 is, for example, a part of liquefied natural gas (LNG) stored in a tank (not shown), and the evaporative gas 12 is, for example, a part of liquefied natural gas in the tank. Is a boil-off gas (BOG) generated by evaporation.

  As seen in FIG. 1, the cryogenic liquid 11 is delivered by the delivery pump 3 and flows into the condensation and mixing device 2. The evaporative gas 12 compressed by the evaporative gas compressor 4 is injected into the low-temperature liquid 11 flowing in the condensing and mixing apparatus 2.

  A booster pump 5 is connected to the outlet side of the condensing and mixing device 2 and condenses and mixes evaporative gas 12 condensed after being injected into the low temperature liquid 11 and mixed with the low temperature liquid 11 in a liquefied state. The mixed cryogenic liquid 11A discharged from the apparatus 2 is pressurized. For example, if the low-temperature liquid is liquefied natural gas, the mixed low-temperature liquid 11A whose pressure has been increased is brought to the vaporizer, gasified again, and then sent to the demand side as city gas.

  As shown in FIG. 2A, the condensing and mixing apparatus 2 includes a horizontal tube-shaped casing 6 in which a venturi-type flow tube 7 is housed, and between the casing 6 and the flow tube 7. Is inserted with an insert 8 made of a woven or knitted fiber metal fine wire such as stainless steel.

  The casing 6 has an inlet portion 6A on the upstream side in the flow direction of the cryogenic liquid 11, an outlet portion 6B on the downstream side, and a flow tube housing portion 6C in which the flow tube 7 is housed and disposed at an intermediate position therebetween. The inlet portion 6A and the outlet portion 6B have the same inner diameter, and the inner diameter is increased in the flow tube housing portion 6C. The axis X that is the center of the inlet portion 6A, the outlet portion 6B, and the flow tube accommodating portion 6C is located on the same straight line. The flow tube accommodating portion 6C has an inner diameter larger than the outer diameter of the flow tube 7, forms a space around the flow tube 7, is dispersed in this space, and the insert 8 is inserted therein. Yes. Further, an evaporative gas injection part 6D that opens upward is formed at the upper upstream side position of the flow tube accommodating part 6C, and the evaporative gas 12 pumped from the evaporative gas compressor 4 is injected into the evaporative gas. Part 6D accepts it.

  The venturi-type flow tube 7 has mounting flanges 9A and 9B projecting radially outward on both sides in the direction of the axis X, and the mounting flanges 9A and 9B are provided in the flow tube housing portion 6C of the casing 6. In addition, the flow tube 7, the inlet 6A of the casing 6 and the axis X of the outlet 6B are attached so that they are aligned and located on one straight line.

  The inside of the flow tube 7 has a reduced diameter portion 7A positioned on the inlet 6A side of the casing 6, a throat portion 7B positioned immediately after the reduced diameter portion 7A, and an expansion extending from the throat portion 7B toward the outlet portion 6B. The diameter portion 7C is sequentially formed. The diameter-reduced portion 7A has a curved surface and the inner diameter is relatively abruptly reduced to narrow the cross-sectional area of the flow path, and the diameter-expanded portion 7C is expanded so as to recover the inner diameter over a long distance in the axis X direction. The throat portion 7B connects the reduced diameter portion 7A and the enlarged diameter portion 7C with a smooth curve so as to be low resistance to the flow of the low-temperature liquid, and is formed to have a minimum diameter so as to have a minimum flow path cross-sectional area. Has been.

  The diameter-expanded portion 7C is divided into a range from the position immediately after the throat portion 7B to the position of the right flange portion 9B in the direction of the axis X, and a plurality of step-shaped diameter-expanded portions 7C-1, 7C-2 ..., 7C-N. Each of the stepped enlarged portions 7C-1, 7C-2,..., 7C-N has a cylindrical inner peripheral surface, and the inner diameter is uniform without changing in the same stepped enlarged portion. Stepped portions 10B-1 and 10B-2 in which the next stepped enlarged portion 7C-2 and the next stepped enlarged portion 7C-3 are formed at the upstream position with respect to the stepped enlarged portion 7C-1. , ..., the diameter is expanded stepwise.

  FIG. 2 (B) shows a stepped enlarged portion 7C-1, as a part of the plurality of stepped enlarged portions 7C-1, 7C-2, ..., 7C-N of the enlarged portion 7C. 7C-2 and 7C-3 are shown enlarged.

  In FIG. 2 (B), the stepped enlarged portion 7C-2 located in the middle in the axial direction has a stepped portion 10B with respect to the radius R of the stepped enlarged portion 7C-1 adjacent on the upstream side. A cylindrical inner surface having a section length L extending in the axial direction is formed with a radius of R + ΔR expanded by a step size of ΔR so as to form −2. On the other hand, the stepped enlarged portion 7C-3 adjacent on the downstream side is similarly expanded in diameter than the stepped enlarged portion 7C-2 and extends by the section length L. In FIG. 2B, the section length L of the stepped enlarged portions 7C-1, 7C-2,..., 7CN is the stepped enlarged portion other than the stepped enlarged portion 7C-N on the most downstream side. However, the section length L may be lengthened as the downstream diameter increases. In addition, the radius of the stepped diameter-enlarged portion has a constant dimension in the axial direction and forms the inner surface of the cylinder. Good. By doing so, the space volume of the step-shaped enlarged diameter portion is further increased, and the space for introducing and condensing the evaporative gas into the low-temperature liquid can be further increased, so that the evaporative gas can be condensed more reliably. Mixing can be performed.

  In the stepped enlarged diameter portion 7C-2, an injection opening 10A-2 of the steam hole 10-2 is located at an upstream position in the region. In the example of FIG. 2B, the upstream side edge of the injection opening 10A-2 is formed so as to be at the position of the stepped portion 10B-2. The steam hole 10-2 is formed so as to penetrate the tube wall of the flow tube 7 in the radial direction, and is inclined inward in the axial direction toward the radial inward. The other steam holes 10-1, 10-3,..., 10-N are similarly upstream of the corresponding step-shaped enlarged diameter portions 7C-1, 7C-3,. The injection openings 10A-1, 10A-3, 10A-N are provided on the side.

  In the present invention, the steam holes 10-1, 10-2,..., 10-N are positioned immediately after the sudden expansion at the stepped portions 10B-1, 10B-2,. The space over the section length L immediately after the sudden expansion at the stepped portions 10B-1, 10B-2,... Can be secured as a sufficiently large space through which bubbles of the evaporative gas flow in the low temperature liquid. A sufficient contact time between the evaporative gas and the low-temperature liquid can be ensured in the space, and the evaporative gas can be cooled, condensed, and mixed with the low-temperature liquid. Further, the evaporative gas is efficiently sucked by the venturi phenomenon efficiently without being affected by the flow of the low-temperature liquid in the flow tube within the space of the stepped diameter-expanded portion.

  The form of the stepped enlarged portion having the stepped portion described above is effective for condensing and mixing the evaporative gas in the low-temperature liquid, but this effect can be achieved by appropriately setting the size of the stepped enlarged portion. Can be played more reliably. For example, if the dimension ΔR of the step portions 10B-1, 10B-2,... That rapidly expands the inner diameter of the venturi-type flow tube 7 is too large, the flow of the cryogenic liquid is disturbed from the position of the step portion, The vapor holes 10-1, 10-2,. As a result, the efficiency of sucking the vapor due to the venturi phenomenon of the low temperature liquid decreases. Accordingly, it is necessary to optimally set the step size for rapidly expanding the inner diameter of the venturi expanded portion.

  Therefore, the inventor conducted various experiments to determine what step size the efficiencies of sucking the evaporative gas into the low-temperature liquid are good. FIG. 3A shows the result of examining the efficiency of suction based on the step size and the venturi phenomenon based on the experiment. The step size ratio is expressed as a ratio (%) of the step size to the immediately preceding radius, that is, a ratio (%) of the step size to the radius of the step-shaped enlarged diameter portion located on the upstream side of the step portion. The efficiency improvement rate is the ratio at which the flow rate of the evaporative gas sucked by the low temperature liquid venturi phenomenon increases compared to when no step is provided, assuming that the power required to flow the low temperature liquid to the venturi pipe is the same. It is expressed as an efficiency improvement rate (%). As shown in FIG. 3A, the efficiency improvement rate is increased by setting the step size in the range of 5 to 40% of the immediately preceding radius compared to when no step is provided, and the step size is set immediately before the step size. It can be seen that when the radius is in the range of 12 to 30%, the efficiency improvement rate is 70% or more and the suction efficiency is high.

  Furthermore, in the present invention, not only the above step radius but also the section length (the length of one section which is the length in the axial direction) of the stepped diameter enlarged portion in which the inner diameter of the venturi expanded portion is rapidly expanded is an appropriate range. We thought that there was, and experimented about this. If the length of one section is short, the transition to the next step-shaped enlarged diameter portion occurs while mixing of the evaporating gas and the cryogenic liquid is insufficient, so that the temperature of only the cryogenic liquid near the vapor hole rises. As a result, since the temperature difference between the evaporative gas and the low-temperature liquid becomes small in the downstream, the evaporative gas is difficult to condense. On the other hand, if the section length is too long, the pressure loss in the venturi tube increases, so that more power is required, and the apparatus becomes larger, leading to an increase in cost. As a result of an experiment on the ratio of the section length dimension, which is the ratio of the section length dimension to the radius of the stepped enlarged portion, and the venturi tube suction efficiency improvement rate (%), as shown in FIG. It has been found that the appropriate size is 2.5 to 8 times the radius of the stepped enlarged portion.

  Next, the evaporative gas reliquefaction apparatus of this embodiment configured as described above and its operation will be described with reference to FIGS.

  First, a part of a cryogenic liquid (for example, LNG) 11 in a tank (not shown) is sent out by the delivery pump 3 and introduced into the condensing and mixing apparatus 2. The evaporative gas generated in the tank is increased by the evaporative gas compressor 4 to a pressure (“intermediate pressure”) between the atmospheric pressure and the city gas operating pressure (4 to 7 MPa), and then the condensing and mixing device 2. To be introduced.

  The low-temperature liquid 11 flows into the flow pipe 7 via the inlet 6A provided in the casing 6 of the condensing and mixing device 2, flows through the reduced diameter portion 7A, the throat portion 7B, and the enlarged diameter portion 7C, and exits from the casing 6. Reach 6B. The cryogenic liquid 11 flowing in the flow tube 7 increases the flow velocity at the reduced diameter portion 7A, reaches the maximum flow velocity at the throat portion 7B, and then gradually decreases the flow velocity at the expanded diameter portion 7C, but the right end at the expanded diameter portion 7C. Since the maximum inner diameter is smaller than the inner diameter of the inlet portion 6A, the flow velocity at the enlarged diameter portion 7C is higher than the flow velocity at the time of inflow of the inlet portion 6A. -Suction power is provided for 2, ...

  On the other hand, the evaporative gas 12 is pressurized by the evaporative gas compressor 4 and injected into the casing 6 through the evaporative gas injection part 6D provided in the casing 6 of the condensing and mixing apparatus 2. An insertion material 8 is inserted into the outer periphery of the flow tube 7 in the flow tube accommodating portion 6C of the casing 6 that accommodates the flow tube 7, and the evaporative gas injection portion is pumped by the evaporative gas compressor 4. The evaporative gas 12 injected from 6D is buffered by the insert 8 and diffuses over the entire circumference and the entire length of the flow tube 7 in the flow tube housing 6C.

  As described above, the low-temperature liquid 11 flowing through the enlarged diameter portion 7C of the flow tube 7 provides a suction force to the vapor holes 10-1, 10-2,. The evaporative gas 12 diffusing in the gas is sucked and introduced into the enlarged diameter portion 7C from the vapor holes 10-1, 10-2,. For example, in the vapor hole 10-2 shown in FIG. 2B, the evaporative gas 12 is sucked from the vapor hole 10-2 and passes through the injection opening 10A-2, and then the step-shaped enlarged diameter portion 7C-. 2 flows in. The injection opening 10A-2 is located on the upstream side in the region of the stepped enlarged diameter portion 7C-2, and the vapor hole 10-2 is inclined upstream toward the radius inward. Are joined under low resistance without countering the flow of the cryogenic liquid 11 in the flow tube 7.

  The stepped diameter-enlarged portion 7C-2 has a diameter that is abruptly increased by ΔR at the stepped portion 10B-2 relative to the preceding stepped diameter-increased portion 7C-1 located on the upstream side. A space over the section length L is formed on the downstream side of the portion 10B-2, and this space can be secured as a sufficiently large space through which bubbles of the evaporative gas 12 flow in the cryogenic liquid 11, A sufficient contact time between the evaporative gas 12 and the cryogenic liquid 11 can be secured in the space, and the evaporative gas 12 can be easily mixed into the cryogenic liquid 11, and the evaporative gas 12 is cooled and condensed by the cryogenic liquid 11 and mixed. Can be made. As a result, the evaporation gas 12 is condensed and reliably liquefied, and flows downstream as a part of the low temperature liquid 11. In this way, the merging due to the inflow of evaporative gas from the vapor hole and mixing into the low-temperature liquid is performed in the same manner in the stepped enlarged portion other than the stepped enlarged portion 7C-2. Thus, the mixed cryogenic liquid 11A containing the re-liquefied evaporative gas is boosted by the booster pump 5 and brought to the vaporizer, then vaporized by the vaporizer and sent to the demand side as city gas.

DESCRIPTION OF SYMBOLS 1 Evaporative gas reliquefaction apparatus 2 Condensation mixing apparatus 3 Delivery pump 4 Evaporative gas compressor 7 Flow pipe 7A Reduced diameter part 7B Throat part 7C Expanded diameter part 7C-1, 7C-2 Step-shaped expanded diameter part 9A Mounting flange 9B Mounting flange 10-1, 10-2 Vapor hole 10A-1, 10A-2 Injection opening 10B-1, 10B-2 Stepped portion L Section length R Radius of stepped enlarged portion ΔR Radius difference (step size)

Claims (4)

It has a venturi-type flow tube in which a diameter-reduced portion that gradually decreases from the upstream side toward the downstream side is followed by a throat portion that has a minimum diameter, and a diameter-expanded portion that gradually increases from the throat portion. In order to inject steam from the outside of the flow tube into the flow tube, steam holes directed in the radial direction and downstream direction of the flow tube are injected into the inner diameter surface of the enlarged diameter portion at a plurality of positions in the axial direction of the flow tube. In a condensing and mixing apparatus that injects steam from an injection opening of a vapor hole into a cryogenic liquid that flows downstream in the flow tube and condenses the vapor to mix with the cryogenic liquid.
The diameter-enlarged portion has stepped diameter-enlarged portions having stepped portions formed at a plurality of positions in the axial direction and having inner circumferential surfaces that are sequentially expanded in diameter in the stepped portion and extend toward the downstream side in the axial direction. A condensing and mixing apparatus characterized in that a steam hole injection opening is provided at an upstream position in the region of the step-shaped enlarged diameter portion.   The radius difference between the preceding step-shaped enlarged portion adjacent to the stepped portion on the upstream side and the succeeding step-shaped enlarged portion adjacent downstream is 12-30% of the inner diameter of the preceding step-shaped enlarged portion. The condensing and mixing apparatus according to claim 1, wherein   The condensing and mixing apparatus according to claim 1 or 2, wherein the stepped enlarged diameter portion extends in the axial direction over a section length of 2.5 to 8 times the radius of the stepped enlarged diameter portion. In the evaporative gas reliquefaction device that mixes the condensed gas generated from the cryogenic liquid stored in the storage tank with the cryogenic liquid dispensed from the storage tank, condenses and reliquefies it,
A condensing and mixing apparatus according to any one of claims 1 to 3, an evaporative gas compressor for compressing evaporative gas, and a delivery pump for delivering a cryogenic liquid from a storage tank. The evaporative gas reliquefaction is characterized in that the evaporative gas is supplied from the upstream side to the flow tube of the condensing and mixing device, and the evaporative gas is injected into the flow tube from the vapor hole of the condensing and mixing device by the evaporative gas compressor. apparatus.

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